College of Dental Medicine

Geriatric dentistry and its instruction are critical in a rapidly ageing population. Japan is the world's fastest-ageing society, and thus, geriatric dentistry education in Japan can serve as a global model for other countries that will soon encounter the issues that Japan has already confronted. This study aimed at evaluating geriatric dental education with respect to the overall dental education system, undergraduate geriatric dentistry curricula, mandatory internships, and graduate geriatric education of a selected dental school in Japan.

Objective-A sequential topical application of calcium and fluoride-phosphate solutions was reported to occlude open dentin tubules, mainly with fluoroapatite precipitates by a rapid ionic reaction, and to be effective at treating dentin hypersensitivity. However, its ability to reduce dentin permeability (Lp) is unknown. The aim of this in vitro study was to evaluate the effect of this treatment on Lp.

This study aimed to compare the dental curriculum of the traditional six-year system with that of the new four-year (graduate-entry) system in South Korea. There are 11 dental schools in South Korea: six are public and five are private. Eight offer the new four-year program and the other three offer the traditional six-year program. Descriptive analyses were conducted using bibliographic data and local information along with statistical analyses such as chi-square tests. In the six-year programs, clinical dentistry subjects were taught almost equally in practical and didactic courses, while the basic science courses were taught more often as practical courses (P < 0.0001). In the four-year programs, both the basic science and clinical dentistry subjects were taught didactically more often; while more dentistry subjects were taught than basic sciences (P = 0.004). The fouryear program model in South Korea is more focused on dentistry than on basic science, while both basic and clinical dentistry subjects were equally taught in the six-year program. (J Oral Sci 54, 191-196, 2012)

This study quantified in vitro the root dentin moisture when 10% formalin (Group A), 3% sodium azide (Group B), and distilled water (Group C) were used as teeth storage media. The root dentin moisture of 66 extracted human mandibular single-rooted teeth was measured at baseline (day 0) and at 1, 3, 7, and 14 days using a digital grain moisture meter. The baseline dentin moisture value was used as a covariate in the generalized estimating equation (GEE) analysis. The mean dentin moisture values (%) ± standard deviation on days 0, 1, 3, 7, and 14 were 10. 6±0.64, 14.3±0.71, 14.6±0.84, 14.4±0.64, and 14.7±0.75 (Group A); 11.4±0.94, 14.6±0.95, 14.6±0.76, 14.6±0.93, and 14.8±0.81 (Group B); and 10.2±0.95, 12.8±0.90, 13.3±0.95, 13.0±0.91, and 13.2±0.89 (Group C), respectively. The dentin moisture increased in all three groups; however, there was no overall significant difference in moisture between the formalin and sodium azide groups.

as an inter-appointment antimicrobial dressing in root canal treatment. The aim of this study was to quantify the particle size and shape of commercialgrade UltraCal XS (UC) and to compare it with that of research-grade Ca(OH) 2 (RG) using a flow particle image analyzer (FPIA). The morphology and penetration inside the dentin tubules of the UC and RG particles were examined using a scanning electron microscope (SEM). UC and RG (10 mg) were mixed with 15 mL of alcohol, and were sonicated. Five milliliters of the dispersion was subjected to FPIA, and particle length, width, perimeter and aspect ratio were analyzed. In addition, UC paste and RG aqueous slurry were agitated on dentin discs and were prepared for SEM examination. There were significant differences between UC and RG with regard to the frequency of different length groups (P < 0.0001). UC contained smaller particles than RG (P < 0.0001). Under SEM, the agitated UC and RG particles occluded the opening of dentin tubules and penetrated inside the dentin tubules. The size of UC particles is smaller than those of RG. Both UC and RG particles were able to penetrate into open dentin tubules. (J Oral Sci 56, 195-199, 2014)

Introduction: Mineral trioxide aggregate (MTA) has been used successfully for perforation repair, vital pulpotomies, and direct pulp capping. However, little is known about the interactions between MTA and glass ionomer cement (GIC) in final restorations. In this study, 2 null hypotheses were tested: (1) GIC placement time does not affect the MTA-GIC structural interface and hardness and (2) moisture does not affect the MTA-GIC structural interface and hardness. Methods: Fifty cylinders were half filled with MTA and divided into 5 groups. The other half was filled with resin-modified GIC either immediately after MTA placement or after 1 or 7 days of temporization in the presence or absence of a wet cotton pellet. The specimens were then sectioned, carbon coated, and examined using a scanning electron microscope and an electron probe microanalyzer (SEM-EPMA) for interfacial adaptation, gap formation, and elemental analysis. The Vickers hardness numbers of the interfacial MTA were recorded 24 hours after GIC placement and 8 days after MTA placement and analyzed using the analysis of variance test. Results: Hardness testing 24 hours after GIC placement revealed a significant increase in hardness with an increase of temporization time but not with a change of moisture conditions (P < .05). Hardness testing 8 days after MTA placement indicated no significant differences among groups. SEM-EPMA showed interfacial adaptation to improve with temporization time and moisture. Observed changes were limited to the outermost layer of MTA. The 2 null hypotheses were not rejected. Conclusions: GIC can be applied over freshly mixed MTA with minimal effects on the MTA, which seemed to decrease with time. (J Endod 2012;38:1126-1129

Dentin moisture content is important in adhesive bonding and structural strength research. However, there is no rapid method available to assess dentin moisture without sample destruction. This study examined the use of a digital grain moisture meter to measure root dentin moisture in vitro. Extracted mandibular single rooted teeth were sectioned at the CEJ. The moisture of the root dentin was measured at six measuring modes for different grains and repeated five times. Dentin weight changes before and after drying were measured to obtain control values. The control values were compared with machine readings. In conclusion, (1) Each non-destructive measurement took less than 30 seconds. (2) 24 hours storage at 37°C and 100 % humidity did not restore dentin moisture. (3) Five grain modes had a high validity, and could be used for dentin moisture measurements.

The aim of this study was to observe particle length, width, perimeter, and aspect ratio of mineral trioxide aggregate finer fractions using Portland cement. The High Power Field mode of the flow particle image analyzer was used for analysis. Images of particle samples were automatically collected by the analyzer along with analysis parameters. Mean, standard deviation, and the number of particles were calculated in each group. Parameters of length, width, and perimeter did not show a statistical significance when groups were compared. Examining the parameter of aspect ratio, there was evidence of a statistical significance seen (pϽ0.05). The cumulative percentage of particles that were between 0.5 and 3 m in size was 88%. Fine particles may penetrate dentin tubules. The average aspect ratio was 0.744 (SDϭ0.155). It can be speculated that a dentin tubule occlusion pattern is dependent on the aspect ratio. (J Endod 2008;34:709 -711)

The aim of this study is to characterize the particle size distribution and circularity of various Mineral Trioxide Aggregates (MTA) (ProRoot MTA/ MTA Angelus/Gray and White) and Portland cements with effective size ranges of 1.5Ϫ160 m using a flow particle analyzer (Sysmex FPIA-3000, Kobe, Japan).Cumulative percentage of particles between 6 and 10 m were, 65, 73, 48, 53, and 70 %, for Gray ProRoot MTA, White ProRoot MTA, Gray MTA Angelus, White MTA Angelus, and Portland cement, respectively. ProRoot MTA contains fewer large particles than MTA Angelus. MTA Angelus contains a higher number of small particles than ProRoot MTA. White MTA contains smaller particles with a narrower range of size distribution than Gray MTA. MTA Angelus particles have relatively low circularity and wide size distribution and are less homogeneous than ProRoot MTA. (J Endod 2008;34:94 -98)

Objective-A sequential topical application of calcium and fluoride-phosphate solutions was reported to occlude open dentin tubules, mainly with fluoroapatite precipitates by a rapid ionic reaction, and to be effective at treating dentin hypersensitivity. However, its ability to reduce dentin permeability (Lp) is unknown. The aim of this in vitro study was to evaluate the effect of this treatment on Lp.